Ignition apparatus



May 25, 1937-. E. B. NowoslELsKl IGNITION APPARATUS Filed July 2, 1935 INVENTOR. -dwafd /Vowos/'e/ Patented May 25,v 1937 PATENT GFFICE IGNITION APPARATUS Edward Nowosieiski, Bloomiieldl. J., assigner to Eclipse Aviation Corporation, East Orange, N. J., a corporation of New Jersey vApplication my z, 193s, serial n129530 10 Claims.

This invention relates to spark-plugs, and more especially to spark-plugs for aviation engines. 'I'he severe service conditions which are imposed on spark-plugs for airplane motors are familiar to those skilled in the art, as is also the importance of enclosing all parts of the high-tension current-carrying system by a continuous metallic shield to prevent interference with the reception of signals by adjacent radio receiving sets, and `also to protect the exposed parts of the ignition system from detriment by the' elements or otherwise.

The object of this invention is to provide a spark-plug, and more especially a shielded spark- 1:, plug, the construction of which is such as to prolong its life and to insure its elfectiveness in such service, and to aord' convenience, and which is economical to manufacture.

The invention comprises novel features of great utility in spark-plugs, and novel combinations of elements making an improved spark-plug and "an improved assemblage of the spark-plug and its high-tension conductor.

Some of the objects are to provide improved electrodes'includingv novel methods of constructing and, assembling the electrodes, and of adjusting the spark gap; to provide improved heat deiiectingand cooling means; and to provide improvements in the m'anner of insulating the cur- 30 rent.

In the drawing. Figures 1, 2, and 3 are views partly in elevation and partlyV in section, each of Figures 1 and 2 illustrating a somewhat different embodiment of the invention. Inmany respects both embodiments correspond to the disclosure .in my co-pending application No. 16,882, illed April 17 1935, and this is particularly true of the features of the disclosure which are claimed in said copending application; and

where identical elements appear in the several l embodiments they are designated bylsimilar reference numerals. I 7

First describing Figure 1, referenceycharacter I fI/ esignates a metallidextenslon of the metallic L15/body I0. As shown this part II extends upwardly considerably above the upper end of the spindle I2 to enclose the spindle and the electrical c nnection between the same and the conductor ch leads the high-tension current to the spin e. This shield extension is preferably inone piece with the attaching nut 5, though f such unity is not necessary.

I provide a cooling and Ventilating chamberV I 3 in the form of an annular space between the shield extension II and a long thin cylindrical (ol. 12s-169)" metallic sleeve I4 having low thermal conducmay, and uned with a. tube l5 formed 5f roues mica constituting the wall of a second chamber IB bounded at its lower end by the upper surface of the compresslble metal gland I l, and at its 5 upper end by a novel heat deflecting andsealingassembly to be further described. 'I'he gland I'I, instead of resting directly upon the lower mica stack I8, as is the usual practice, is in contact with the upper end 2l of a sleeve 22 provided l0 for the purpose of absorbing the heat which finds its way into the mica stack I8 and deecting said heat to the gland II and outer wall of ther plug.

Two other heat defiecting sleeves are shown at 15 23, and. 24, the former resting on the upper surface of the electrode cup 25 secured in position 'on the base of the spindle I2 by a pressure sufficient to change-the cross-section of the upper end of the cup (initially of uniform bore) and 20 cause its contour to conform to that of the spindle base. The part 24 is in the nature of a continuous jacket enclosing the spindle I2 and its insert 2l of some metal (such as copper or silver) having higher conductivity than the material- 25 steel, preferably-used in the spindle proper. This sleeve or jacket 24 is shown as closed at its lower end but this closure occurs `onlyt fter the jacket has been positioned upon the spindle, the 'jacket being initially, merely a thin-tube 30 open at either end. After being placed around the spindle the extending portion of the lower gend is bent'inwardly to lle fiat against the bottom surface of the spindle I2 and its insert 21. It will be noticed further that the jacket 24 ex- 35 tends upwardly to a point just above .the end of the gland II and the point where the cen- Y trally bored portion of the spindle begins. Due

to the reduction in cross-sectionaLare'a at this point, and also by reason of the termination of 40 the jacket 24 at this point, there is a tendency to ct of! much of the upward flow of heat through the spindle I2 and to deflect the heat ilow outwardly and radially into the copper gland r Il from which much of the heat is directly dis- 4" sipated by the cooling blast circulating adjacent washer 38 seated on the central `ledge of the gland Il, such circulation being produced by reasonof the radial openings 32 and the annular chamber 33 communicating therewith. The 50 sleeves 23 and 22 coact with the jacket 24 in divertin heat from the spindle I2 and the electrode 25 to the annular chamber 34 and the copper gland I7, and from said chamber 'and r gland to the atmosphere by way of shell I0 and 5" plied to theA gland I1 to insure a firm bond ora,

these radial openings 32 there is provided a thrust washer 38 through which pressure is apseal along the taper of the gland, thus preventing the escape of the confined cylinder gases, the pressure being applied as a result ofthreading the shield extension into the shell I0, the'two elements just mentioned being correspondingly threaded as indicated at 4|.

The spindle I 2 is of reduced diameter at two or more points as indicated at 43 and 44; and

the jacket 24, the rolled mica tube 46, and the v soft metal gland I1 are pressed snugly against these peripheral depressions in the spindle as one of the plug assembling operations. This operation o applying pressure laterally results not only in a firm seal around the spindle I2 but also eliminates any longitudinally extending crevices or pipes which have heretofore been I a source of leakage characteristic of rolled mica insulating tubes. The wrapping of the mica sheets one around the other tends to leave such crevices running longitudinally of the wrapping, but by producing kinks at several points along the length of the wrapping, as indicated, I have found it 'possible to eliminate this source of trouble. v

As a means of maintaining the mica stack 43 in the compressed condition and at Ytha-sanne time applying radial pressure to hold th mica lining I5 of the inner metallic sleeve I4 in posi#` tion, and at the same time effecting an additional path for the transfer of heat directly to the said sleeve I4 from which itmay be radiated to the atmosphere by the cooling current of air flowing along the chamber I3 and the radial apertures 20 and 26, I propose t peen or otherwise upset the upper edge of spindle I 2 to hold it Vfil-'mJy against a metal sleeve`52'which is flanged at its lower en d to receive an outer sleeve 53 located in place by a washer 54 adapted to form a seat against which'sleeve 52 is rmly bonded by the same upsetting action as that which binds the spindle top thereto. These parts 52 and 53, when subjected to this upsetting pressure applied to the spindle top, act upon `the lower washer, 56 to compress the mica stack 48 and at the same ytime press against the expansion ring 58 to cause the latter toy grip the mica lining I5 at a point approximately. midwayv between its ends, this lining 58 beingvinserted and expanded in the tube I4 prior to the assembly of said tube within the'shield extension II.

By the process above described the. cap assembly and spindle, that is, the parts l2, 54, 53,

52 and 56, become a permanently integrated unitwhich, by reasonfof its extremely tight (but somewhat resilient) tit with the ring 58, is capable of transferring considerable heat from the ,i upper part of the plug to the radiator tube I4.

This heat transfer is accelerated by reason of the shunting effect of the asbestos heat barrier 59,

and an additional asbestos lheat barrier shown at 60.

After the cap assembly has been secured by the upsetting process abovev described, there lis inserted within the hollowed portion of the spindle, a coil spring 6| having itsupper end extending upwardly into position`to contact the radially spread strands of the current conducting wire 86 when the latter is installed in place. Associated with the wire 66 is its'covering 61 of insulating material, its outer metallic sheathf68, the swivel connection 69 soldered or otherwise seelectrode 25 across which annular space the ignition current may pass, but normally does not, as there is a shorter path to the horizontally disposed transverse portion 93 which is preferably built up by taking two or more elements and uniting them successively to the convex surface of the cup shaped member 9| through the instrumentality of a thin cup-shaped `liner of soft metal (such as copper) which, upon application of a high temperature, will fuse suiciently to form a permanently welded connection with the parts 9|, 93 and 96, the two last named being similarly welded by the action of the heat upon the soft metallic lining .91 interposed there- IVbetween. This assembling process also includes as its. flrst step the placing of the outer shell 'III on a suitable table or tray with its lower,

counterbored portion 94 uppermost, then insert.

in a hydrogen gas furnace or other suitable heat chamber where it may be subjected to a temperature sufficient to cause a. fusion or welding along the surface of the elements 94, 98, 96,91, 93, 95 and-9I- with the result that' allthese elements become fused into a permanently Welded single unit. This unit is then removed from the furnace, and-the core assembly, the shield extension assembly, and the uppervcable assembly* successivelyI attached thereto i-n' the respective manner heretofore indicated. When this complete assembly has. been accomplished it will be `found that the inner electrode 25 occupies a position approaching that of the transverse portion 93 of the outer electrode and also approaching that of the inner cylindrical edge 92 of the thimble 9|, forming an auxiliary spark gap, the

clearances therebetween being such that the spark will normallyejump from the relatively broad surface of the electrode 25 to the correspondingly broad plane surface of thf: cros'spiece93 of' the ground electrode; but if for any reason this normal path of the spark is obstructed-as for example by the formation of ice particles-#the spark can then jump from` the cylindrical surface of the electrode 25 to the above described cylindrical surface 92 of the thimble 9| which maytherefore be considered as a part of the completed electrode. In fact, it is of course, possible to have the elements 92, 9| and 96 originally formed as an integral whole rather than being composedrof three subsequently united pieces as shown.

It will be noted that the mica tube 45 terminates somewhat above the lower flange of the heat conducting sleeve 23 of copper or other metal, and that therefore a plurality of the mica disks I8 lie between the end of the mica tube and the said flanged portion of the sleeve. This arrangement has the advantage of facilitating maximum heat transfer from the mica assembly I8 and deilecting such heat to the the cylindrical portion of the sleeve 23 is exment 25 with the spindle |2 (or ||2, as the case ternally tapered to facilitate a snug grip and seal between parts 45j 23 and 24.

In the second embodiment of the invention, as shown in Fig. 2, there are many elements which are identical in their structure arrangement and functioning to the elements designated by corresponding reference characters in Fig. 1, and these corresponding elements will) now be further discussed in detail. 'I'he dierentiating elements are as follows:

In place of the transversely extending electrode 93, 95 of Fig. 1 I have shown in Fig. 2 a

, simpler form of electrode including a single surrounding member |09 adapted to be fused to the counterbored portion 9d of the shell with theparts 25 and |09, the opposingsurface of which Fig. 1.

' its mica lining |5 in close contact. A the spacer |2`| is peripherally grooved as indiparts have non-conforming contours to make such spark gap variation possible.-

The further differentiating feature of the embodiment shown in Fig. 2 is the elimination of the upper thin walled section of the central spindle and the substitution of a central spindle ||2 which terminates adjacent the upper end of the member at which point the enclosing jacket 24 also terminates. With this revised construction the transfer of the ignition current to the spindle occurs by way of the lower plane surface ofthe cylindrical block H3 of carbon or carbonaceous material ratherthan through the lateral surface thereof as inthe construction shown-in Fig. 1. The current is fed to the block ||3 by the coil .spring 6| in the same .manner as in the construction of Fig. ibut instead of being guided by the upper extension of the spindlesaid spring 6l is guided and positioned by the presence of an apertured cap ||4 having a downwardly extending shank ||6 which together with the upper portion. .serves to enclose and .retain the upper end of the mica wrapper 46. The member Ill also constitutes a means of applying pressure to the annular retainer III or the mica assembly I8 and further operates to hold in place the expansion ring IIS corresponding to ring .58 of the construction shown/ An additional differentiating feature inthe embodiment shown in Fig. 2 is .the ltion of the outwardly flaring upper end of the radiator tube I4 and the substitution of a spacer `ring |2| acting in conjunction with an annular cap |22, to retain the upper end of the tube Il and Preferably,

cated at |20 tto reduce the amount of metal at this point and thereby retard heat-now in this direction.

In Fig. 2 the jacket |24, instead of extending to the base of the spindle (as in rig. 1) nares outward to form a'iiange |23 acting asia base for mica assembly i8 and mica 46. A thin cap |24a is rstrplaced over the lower end of the spindle, and the electrode cap 25 is then attached. and forms a base for ange |23.

The n'ovel method n: integrating eleetmde eiemay` be) is indicated in Fig. 3. Referring to said figure, it lwill be seen that the member 25 is originally in the shape of a cup having a straight bore sufliciently wide to t over the jacketed end of the spindle. After assembly in this fashion, pressure is applied to cause the open end of the cup to close in against the reduced section of the spindle (just above the Wider base) changing the shape of the cup to the extentA indicated in Figs. 10 1 and 2, and thus making it undetachable from4 the spindle. In addition to this step of applying pressure to upset or mushroom the member 25, there may be a further step of applying heat to a sufcient degree to fuse the parts and vH2, the jacket |240. acting as the iiux agent in the same fashion as in the fusing of parts 33 and 96 in Fig. l. In the event that the intermediate member |2411 is omitted, the union will be eiected directly between parts 25 and 20- disclosed in one or more of my co-pending applications numbered 16,882; 62,524; 121,216; 121,217; and 134,396, led. April 17,. 1935, February 5, 1936, January 18, 1937, January 18, 1937, and April 1, 1937, respectively, reference is to be made to said co-pending applications, or divi- 35 sions thereof.

What is claimed is:

1. In a spark plug adapted to receive a high tension lead, and having a central spindle and a centralelectrode integrated 'with the base of said 40 spindle, a sleeve of high thermal conductivity surrounding said. spindle, said sleeve having a flanged base resting on the upper surface of said electrode,

a secondsleeve of insulating material surrounding said erst-named sleeve and extending beyond the upper end of said spindle, a non-metallic block .resting on the upper end of said spindle to conduct current thereto, said block being of lower thema] conductivity than said first-named sleeve, and means extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said block.

2. In a spark plug adapted to Areceive a high tension lead, and having a central spindle and a central electrode secured to the base oi' said spin'- 55 dle, a sleeve of high thermal conductivity surrounding said spindle, said sleeve having a anged base resting on the upper surface of said electrode,

'a second sleeve of insulating material surrounding said iirst-named sleeve and extending beyond the upper end of said spindle, a non-metallic block resting on the upper end of said spindle to conduct `current thereto, said block being of lower thermal conductivity than said mst-named sleeve, means A extending beyond the upper end of said insulating sleeve to electrically connect said high tensionlead with said block, and a barrier to heat iiow surrounding said last-named means.

3. In a spark plug adapted to receive 4a. high tension lead, and having a central spindle and 'a central electrode integrated with the base of said spindle, a sleeve of high thermal conductivity surrounding said spindle, said sleeve having a -iiangedbaserestin`gontheuppersmfaceofsaid electrode, a second sleeve of material surrounding said rst-named sleeve and extend-- ing beyond the upper end of said spindle, a non- .metallic block resting on the upper endoi said spindle, to conduct current thereto, said block be- .ing of lower thermal conductivity than said rstcentral electrode secured to the base of said spindie, a sleeve of high thermal conductivity surrounding said spindle, vsaid sleeve having a iianged base resting on the upper surface of said electrode, a second sleeve of insulating material surrounding saidfirst-named sleeve and extending beyond the upperend of said spindle, a carbonaceous block resting on theV upper end of said spindle to Vconduct current thereto, said block being of lower thermal conductivity than said firstnamed sleeve, and means extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said block.

5. In a spark plug adapted to receive a high tension lead, andv having a central spindle, a sleeve of high thermal conductivity surrounding said spindle, a second sleeve of insulating material surrounding said first-named sleeve and extending beyond the upper end of said spindle, a

non-metallic "block resting on the upper end of said spindle to conduct current thereto, said block being of lower thermal conductivity than said first-named sleeve, and means extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said block.

spindle to conduct current thereto, said block being of lower thermal conductivity than said firstnamed sleeve, and means extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said mock.

7. In a spark plug adapted to receive a high tension lead, and having a central spindle,a sleeve of highthermal conductivity surrounding said spindle, a second sleeve of insulating material surrounding said iirst-named sleeve, a non metallic block in -contact with said spindle to conduct current thereto, said block being of lower thermal conductivity than said first-named sleeve, and means extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said block.

8. In a spark plug adapted to receive a high tension lead, and having a central spindle, a sleeve of high thermal conductivity surrounding said spindle, a second sleeve of insulating material surrounding said rst-named sleeve, a nonmetallic block inlcontact with said spindle to conduct current thereto, said block being of lower thermal conductivity than said first-named sleeve, and means extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said block, and a barrier to heat flow surrounding said last-named means.

9. In a spark plug adapted to receive a4 high tension lead, and havinga central spindle, a sleeve of high thermal conductivity surrounding said spindle, a second sleeve of insulating material extending 'beyond the upper end of said spindle, a block resting on the upper end of said spindle to conduct current thereto, said block being of lower thermal conductivity than said rst-named sleeve, and means .extending beyond the upper end of said insulating sleeve to electrically connect said high tension lead with said block.

lll. In a spark plug adapted to receive a high tension lead, and having a. central spindle, a sleeve of high thermal conductivity surrounding said spindle, a second sleeve of insulating material.

surrounding said rst-named sleeve, a block in contact with said spindle vto conduct current thereto, said block being of lower thermal con- Y ductivty than. said rst-named sleeve, and means 

